1. Field of the Invention
The present invention relates to a structure of mounting a fuel injection valve to a fuel distribution pipe, in which an annular connecting groove is defined in an outer peripheral surface of an intermediate portion of a fuel injection valve which has, at one end thereof, a fuel injection portion inserted in a fuel injection bore in an engine and at the other end thereof, a fuel inlet portion inserted in a fuel supply port in a fuel distribution pipe; a connecting flange is formed in the fuel supply port and aligned axially with the connecting groove; a collar portion and a locking groove are engaged with the connecting groove and the connecting flange, respectively, and are provided in a connecting member for resiliently clamping the fuel injection valve and the fuel supply port from opposite outsides.
2. Description of the Related Art
Such structure of mounting the fuel injection valve to the fuel distribution pipe is conventionally known, as disclosed in Japanese Patent No.2,837,268, for example. In such structure, a pair of positioning recesses in the connecting member are engaged with positioning projections formed on outer surfaces of the fuel distribution pipe and the fuel injection valve, respectively in order to position the fuel injection valve in a rotating direction on the fuel distribution pipe.
In a structure in which the positioning of the fuel injection valve in the rotating direction on the fuel distribution pipe is carried out through the connecting member, as described above, positioning engage portions are required at two places between the fuel distribution pipe and the connecting member and between connecting member and the fuel injection valve. For this reason, backlashes (clearances) in the engage portions inevitable in the manufacture are accumulated, resulting in a degraded accuracy of positioning of the fuel injection valve. Thus, when the fuel injection valve has been mounted in an engine, a deviation is liable to be produced in the direction of injection of fuel from the fuel injection valve. When the fuel distribution pipe and the fuel injection valve are connected to each other by a single connecting member, the following disadvantage is encountered: The engagements must be carried out simultaneously at four places (1) between portions of the connecting member and the fuel distribution pipe for axially connecting them, (2) between portions of the connecting member and the fuel injection valve for axially connecting them, (3) between portions of the connecting member and the fuel distribution pipe for positioning them in the rotating direction, and (4) between portions of the connecting member and the fuel injection valve for positioning them in the rotating direction. In this case, a deal of skill is required for such assembling operation, and the assemblability is remarkably poor.
The present invention has been accomplished in view of such circumstances, and it is an object of the present invention to provide a structure of mounting a fuel injection valve to a fuel distribution pipe, wherein the fuel injection valve can be easily connected to the fuel distribution pipe, while enhancing the accuracy of positioning of the fuel injection valve in a rotating direction on the fuel distribution pipe.
To achieve the above object, according to a first aspect and feature of the present invention, there is provided a structure of mounting a fuel injection valve to a fuel distribution pipe, in which an annular connecting groove is defined in an outer peripheral surface of an intermediate portion of a fuel injection valve which has, at one end thereof, a fuel injection portion inserted in a fuel injection bore in an engine and at the other end thereof, a fuel inlet portion inserted in a fuel supply port in a fuel distribution pipe; a connecting flange is formed in the fuel supply port and aligned axially with the connecting groove; a collar portion and a locking groove are engaged with the connecting groove and the connecting flange, respectively, and are provided in a connecting member for resiliently clamping the fuel injection valve and the fuel supply port from opposite outsides, wherein a positioning bore is provided in the connecting flange, and a positioning projection is formed on the fuel injection valve so as to be brought into engagement in the positioning bore simultaneously with the insertion of the fuel inlet portion into the fuel supply port.
With the first feature, the positioning of the fuel injection valve in the rotating direction on the fuel distribution pipe is carried out only by the engagement of the positioning projection of the fuel injection valve in the positioning bore in the fuel distribution pipe at one place. Therefore, there is no accumulation of backlashes in engage portions and hence, it is possible to enhance the accuracy of positioning of the fuel injection valve in the rotating direction. Moreover, the axial connection of the fuel distribution pipe and the fuel injection valve by the connecting member is necessarily conducted after the positioning of the fuel injection valve in the rotating direction. Therefore, the positioning operation and the connecting operation can be carried out sequentially and extremely easily, leading to an extremely good assemblability.
According to a second aspect and feature of the present invention, in addition to the first feature, at least one of the positioning projection and the positioning bore is formed to be convergent toward the fuel inlet portion.
With the second feature, the engagement of the positioning projection and the positioning bore with each other can be conducted easily, and after such engagement, the backlash between both of the positioning projection and the positioning bore can be reduced to further enhance the accuracy of positioning of the fuel injection valve in the rotating direction.
According to a third aspect and feature of the present invention, in addition to the first or second feature, the connecting groove and the positioning projection are formed integrally in an outer skin formed from a synthetic resin by molding to cover an outer periphery of a coil of the fuel injection valve.
With the third feature, the connecting groove and the positioning projection can be formed along with the outer skin made of the synthetic resin on the fuel injection valve, and a post-processing is not required, which can contribute to a reduction in cost.
According to a fourth aspect and feature of the present invention, in addition to any of the first to third features, the positioning projection is provided with a step for abutting against the connecting flange to define a depth of insertion of the fuel injection valve into the fuel supply port.
With the fourth feature, when the depth of insertion of the fuel injection valve into the fuel supply port is defined by the abutment of the step of the positioning projection on the fuel injection valve against the connecting flange of the fuel distribution pipe, a distance between the connecting groove in the fuel injection valve and the connecting flange of the fuel distribution pipe is constant. Thus, the collar portion and the locking groove of the connecting member can be brought precisely into engagement with the connecting groove and the connecting flange, respectively, leading to a further improved assemblability, and an automatic assembling using a robot is feasible.
According to a fifth aspect and feature of the present invention, in addition to any of the first to fourth features, the positioning projection is formed so as to be connected to a bottom of the connecting groove.
With the fifth feature, the root of the positioning projection is thickened and increased in strength, whereby the strength of a portion of the injection valve around the connecting groove can be also increased.
The above and other objects, features and advantages of the invention will become apparent from the following description of the preferred embodiment taken in conjunction with the accompanying drawings.